Energy storage devices that accumulate energy such as recovered brake energy temporarily in order to conserve energy for vehicles etc. have been taken note of. A flywheel device that stores rotational energy of a rotating body rotating at high speed is one such device. A flywheel can provide an energy storage device that accumulates energy acquired from a drive force transmission system of a vehicle as energy of rotation of a flywheel that is then discharged as necessary. For example, when a vehicle decelerates, kinetic energy of the vehicle is recovered via a drive force transmission system. Accumulated energy is then returned to the drive force transmission system so as to assist acceleration when the vehicle accelerates. An auxiliary device for power source is driven by the accumulated energy. For example, a hybrid-type electric vehicle provided with a flywheel includes a flywheel driver generator that rotatably drives the flywheel and generates electricity as a result of rotation of the flywheel, an axle drive generator that rotatably drives an axle and generates electricity using braking energy of the axle, a battery that stores electrical energy at the time of actuation, a generator that generates electricity to rotatably drive the axle drive generator, and a power controller that controls the flywheel driver generator and the axle drive generator. The power controller then ensures that electricity is generated by the flywheel driver generator when vehicle drive power is greater than the electricity generating output of the generator, and ensures that energy is stored at the flywheel using surplus electrical power when the vehicle drive power is less than the generated electrical output and using electrical power generated at the time of braking.
However, a gyro moment is generated because the flywheel device has a rotating mass that rotates at high speed. This gyro moment therefore provides a force that tilts the vehicle body and a force that changes the orientation of the vehicle body. This may be detrimental to the motion of the vehicle body. Devices, such as a double gimbal device, that counteract gyro effects with respect to motion and swing of the vehicle have therefore been proposed. On the other hand, flywheels also have problems from the point of view of mass and size and also demand additional merits in addition to energy storage.
In patent document 1 (JP 11-69511 A), a vehicle drive device is disclosed that suppresses the generation of gyro moment at the flywheel and improves both the efficiency of energy storage and the travelling stability of the vehicle. Specifically, a generator-motor controller controls electrical power supplied to a first generator-motor based on an accelerator signal and a brake signal. Surplus electrical power is then stored in a battery or stored in the flywheel as energy. Electrical power deficiencies are made up for by converting energy stored in the flywheel to electrical power using a second generator-motor for supply to the first generator-motor. The flywheel is supported at a double gimbal bearing. A flywheel attitude controller drives a servo motor in response to swing of the vehicle. The generator-motor controller then controls attitude so that the flywheel does not swing on the absolute coordinates. This device improves the travel stability of the vehicle by eliminating the detrimental influence of the flywheel by controlling the “flywheel attitude” and the flywheel is merely used for energy storage.
A vehicle mounted flywheel type electrical power storage device and a vehicle body attitude control system for a vehicle using this device are disclosed in patent document 2 (JP 2005-65411 A). Patent document 2 disclose technical means that controls the vehicle body by preventing inertial force of the flywheel from having a detrimental effect on the behavior of the vehicle body of the vehicle. Specifically, a flywheel unit having a flywheel rotatably driven by an electric motor capable of generating electricity and a gimbal structure equipped with two rotation supporting units that provide support to this flywheel in a freely rotatable manner about each of an x-axis and a y-axis are provided at a vehicle mounted flywheel type electrical power storage device. A rotation angle sensor (rotation angle detection means) that detects each rotation angle of the flywheel unit at least two rotation supporting units is also provided. Behavior of the body of the vehicle can then be detected by a behavior detection unit provided at a control unit from the detection results of the sensors. More specifically, the flywheel is made to function as a rotor of a gyroscope and a steering wheel and shock absorbers etc. are driven so as to cancel out rolling (for example) by outputting the instruction signals to the steering system and suspension system based on the detected behavior of the vehicle body. The flywheel functions merely as a rotor (detecting means) of the gyroscope in addition to an energy function.
It is therefore an object of the present invention to control rolling motion of a vehicle by eliminating the detrimental influence of gyro moment on the motion of the vehicle and actively using gyro moment generated by a flywheel constituting an energy storing device.
It is another object of the present invention to provide a support structure for a flywheel that is capable of actively employing gyro moment generated by the flywheel.